1. Field of the Invention
The present invention is related to lockable valves for controlling fluid flow in flow lines. More particularly, the present invention pertains to security devices for selectively preventing unauthorized activity involving use of a fluid obtainable by passage through a flow line.
2. Description of the Prior Art
Security devices have been designed for preventing unauthorized use of an engine operable on fluid fuel whereby a valve is closed to prevent the fuel from being transmitted from the fuel supply to the engine. The valve is locked in the closed position, and may be returned to the open position, thereby permitting transmission of the fluid fuel to the engine, only by use of a key or combination to release the locking mechanism. U.S. Pat. Nos. 1,303,878; 1,600,050; 1,713,635; 3,773,139; and 3,792,712 describe such locking valves, and show a variety of means for effecting the locking of the valve in the closed configuration. Particular attention is devoted to the application of such security devices to motor vehicles, such as automobiles. U.S. Pat. No. 2,115,784 shows a lockable valve mounted adjacent the engine of an automobile, and connected by a shaft and joint combination to an actuating mechanism on the dashboard of the vehicle. U.S. Pat. Nos. 2,881,789 and 3,776,263 disclose lockable fuel line valves which may be mounted in the floorboard of a motor vehicle while extending below the floorboard to be incorporated in the fuel flow line between the gasoline tank and the vehicle engine. The valves may be operated from within the vehicle by inserting a key in the lock mechanism exposed to the interior of the vehicle through the floorboard. Both such valves employ rotary lock mechanisms, with the valve of U.S. Pat. No. 3,776,263 converting the rotary motion of the locking mechanism into translatory movement of a valve body into and out of sealing engagement with a seat. The valve shown in U.S. Pat. No. 2,881,789 directly links the rotary motion of the locking mechanism to rotation of a plug valve.
Another prior art security valve employs a plunger type locking mechanism, and is also mountable in the floorboard of a motor vehicle for operation from within the vehicle. With such a locking mechanism, the valve may be closed and locked in the closed configuration by the operator simply depressing the plunger of the locking mechanism. Rotation of an element of the plunger with the use of a key releases the plunger to be returned to the open configuration by a spring mechanism within the locking mechanism itself. Within the valve body, the plunger of the locking mechanism carries a valve stem which presses a resilient seal against an annular seat surrounding an outlet port. The outlet port communicates through the bottom of the housing to that portion of the fuel flow line leading to the engine. When the plunger of the locking mechanism is raised, the valve stem is withdrawn from the pressing engagement with the resilient seal and the seat, and the outlet port then communicates with an inlet port. That portion of the fuel flow line extending from the fuel tank communicates with the inlet port. Tubing fittings join both segments of the fuel flow line to the housing. The housing itself is constructed of two metal components which are held together by screws. Screws are also employed to anchor the locking mechanism in one portion of the housing. The union of the two housing components also serves to anchor the resilient diaphragm which provides the resilient seal between the valve stem and the seat. This anchoring of the diaphragm occurs between an annular lip on one housing component facing an annular shoulder on the other housing component.